Kondo-destruction quantum criticality in the particle-hole asymmetric Bose-Fermi Anderson model

Critical destruction of the Kondo effect is believed to underlie beyond-Landau quantum criticality in a number of heavy-fermion metals [1]. Insight into the phenomenon can be obtained from Bose-Fermi impurity models, which arise in extended dynamical mean-field descriptions of heavy-fermion quantum criticality [2]. This talk addresses the Bose-Fermi Anderson model with a power-law bosonic bath having an exponent s < 1 and a fermionic band with a density of states that vanishes at the Fermi energy as ρ(ε) ∝ |ε-ε_F|^r with r > 0. We focus on the regime r > ½ in which criticality occurs only away from particle-hole symmetry, using a continuous-time quantum Monte Carlo method for both spin-isotropic and Ising-anisotropic variants of the model, and the numerical renormalization-group method for Ising anisotropy. We examine the nature of the dominant critical fluctuations for different combinations of r and s, finding that the criticality groups into fundamentally different classes. We discuss the difference in our conclusions from those reached on the basis of a double epsilon-expansion approach [3].

[1] S. Paschen and Q. Si, Nat. Rev. Phys. 3, 9 (2021).

[2] Q. Si, S. Rabello, K. Ingersent, and J. L. Smith, Nature 413, 804 (2001).

[3] D. G. Joshi et al., Phys. Rev. X 10, 021033 (2020).